This invention pertains to the art of flexible hose assemblies and more particularly to metal hose assemblies. The invention is applicable to modifying a braid ring as conventionally used in a flexible hose assembly and will be described with reference thereto. However, it will be appreciated that the invention has broader applications and may be advantageously employed in other environments and applications requiring a modified braid ring.
Known methods of assembling a flexible metal hose use a braid ring located at one end of a helical or annular corrugated tube that is surrounded by a metal braid. The braid ring is dimensioned for close receipt over the tube and braid and facilitates termination of the hose assembly. Usually a fitting is abutted against the ends of the tube, braid and braid ring for subsequent welded or brazed interconnection of the various components.
Although a number of different fittings can be used as desired or required for a particular purpose, oftentimes a fitting incorporating a hex surface is used. The fitting is normally machined from bar stock and, if the fitting is to include a hex surface, slightly greater diameter bar stock is required and more machining is necessary to form the hex surface. For example, a male pipe fitting would require a simple external threading of a tubular workpiece where the workpiece is substantially identical in outer dimension to the completed fitting. Adding a hex surface to the male pipe fitting requires a substantially larger diameter workpiece for the same size threads because of the enlarged dimension of the hex surface. Therefore, a much greater amount of machining is required to reduce the diameter of the workpiece before the pipe threads are formed. Still further, the conventional incorporation of a hex surface on the fitting requires use of a longer fitting where in some instances the shortest possible fitting length is desired.
In other limited instances, a hex piece is added to a fitting that otherwise does not include a hex arrangement. The hex piece includes a smooth bore that is slipped over the fitting, e.g. a pipe nipple, to effect a hex arrangement.
Users of the flexible hose assembly often incorrectly grip the end of the hose assembly around the braid ring. The "damage" to the hose assembly is often no more than mechanical compression due to the light weight of the braid ring, and the hose being heat effected under the band. Nevertheless, this also imposes undue torque and stress on the hose at the base of the welded connection.
A certain amount of skill is also required to terminate the hose and join the fitting thereto. In the U.S., single pass welding is very seldom used, and even then, only in particular situations or after special setup. Instead, plural welds are required to complete the assembly. A first weld interconnects the corrugated tube, braid and braid ring. Thereafter, a second weld joins the fitting to the tube, braid and ring. It will be understood by those skilled in the art, though, that the subject invention is applicable to single or multiple pass welding, brazing, soldering, or fusion bonding.
Accordingly, it has been deemed desirable to manufacture flexible metal hose assemblies by eliminating the need for a hex head on the fitting, improve the weldability thereof, and provide a surface to effectively grip the end of the hose.